F5m kit

[Russellc]

Tried and watched the bias go to about 1.5 amps per side. I will probably buy a bigger pair of sinks and fab an expanded metal of some kind for a lid.

My F5 has a solid top cover. Rather than drill it full of ratty looking holes, I just used an extra nut as spacer to raise it about a quarter inch all the way around.

 

[seventenths]

Nice idea on the sheet pan. I cut aluminum by using a jig saw, then some clamps and a 2x4 for sanding a straight edge . I then use a belt sander (3x21or 3x24 is a good size) makes almost perfect results.Need to file the sharp edge with a file of course. I suppose a table saw with a metal blade would also work well. I assume one could use a masonite or plywood backer for thin gauges.

Aluminum cuts great on the TS with an 80 tooth carbide blade. Cheap is fine. Your assumed backer material is perfect. Dude I knew bought a Unisaw from Boeing Surplus. It has been used exclusively for aluminum years.
Looking forward to seeing it come to life. Cheers
Add: I cut 1'x1" t-slot aluminum exclusions and it's like butter

 

[BeardyWan]

Does someone happen to know the max Capacitor diameter that works for the PSU board?

 

[Nelson Pass]

1.2 Inches.

 

[Holzarbeiter]

Important to note that I have made a minor improvement in the power supply boards detailed here.

I bought the original F5m Kits but I can't figure out how to wire them Dual Mono.

With the improved Power Supply Boards coming soon specifically designed for MonoBlocs, is this now the only way to run F5m Dual Mono? Is there a way to convert the original boards?

Hopefully the store will allow more then one kit to be purchased at one time. And/or boards listed separately given consideration.

 

[Nelson Pass]

Actually, all I did was to put some extra pads on the boards to connect the V+ to V+ and V- to V-.

On the earlier boards with just the one thermistor on each polarity they are already paralleled.

 

[gary s]

1.2 Inches

That is 30mm for us metric followers.

 

[twofires]

I was going to ask the same capacitor diameter question, but now that has been answered (thanks!) I'll ask a different one - is there a point at which extra capacitance is going to cause issues? I see that people sourcing their own components are going above (sometimes well above) the 4700uF x12 supplied in the kit. I was thinking a 500VA supply with 10000uF x12 caps. Would we call that robust, or ridiculous? Those who have already built one, what capacitance are you running with?

 

[seventenths]

Not ridiculous at all. The "std" FW supply is 8 x 15,000 I believe.

 

[coffee-fan]

I am planning to use these power entry modul and would like to ask what kind of fuse 5x20 mm is recommended?

 

[Dennis Hui]

You want an appropriately sized time-delayed/slow blow fuse. A good rule of thumb is the transformer's VA rating / mains AC voltage. For example, my mains voltage is ~120VAC and I use a 2.5A slow blow fuse with a 300VA transformer.

 

[BeardyWan]

I would imagine that if you increase the capacitance then at some point the first current limiting thermistor may need to be swapped out for something bigger.

 

[Holzarbeiter]

current limiting thermistor

Does anyone know the part # of the green Thermistor mounted on the wire terminal block? It is not listed in BOM provided in kit. Identifier stamped SCK 108. Searching for that does not come up.

 

[WBS]

That was a freebie included by Nelson from his Pass Labs/First Watt stash. IIIRC it is a high quality industrial part that is no longer available at retail.

 

[poseidonsvoice]

@Holzarbeiter
Here is what I get from a search.

Best,
Anand.

 

[seventenths]

@Holzarbeiter In prior FW Pwr supplies a CL60 is used

 

[Holzarbeiter]

That was a freebie included in the kit by Nelson

Thanks!

Could a CL-60 or derivative take it's place in a Dual Mono amp?

I can't read the data sheet to compare as there is no info I can find. on the green part.

 

[Holzarbeiter]

Anand-

Your search is fantastic. I can't come up with that at all in google. I will look the page over you linked.Octopart come up empty for me as well.

THANKS

 

[Holzarbeiter]

In prior FW Pwr supplies a CL60 is used

If I can't find green I will try. I don't think it would hurt...

Thanks!

 

[seventenths]

It is absolutely fine. The circuit is stripped down but the PS requirement are the same. The new PS design appears to be an effort to make construction more affordable. Many, myself included are running the circuit with the traditional FW design